ABSTRACT The sansalvamide A (San A) scaffold is a promising structure for the development of novel cancer therapeutics. We have used the San A scaffold to produce 7 compounds that are cytotoxic to pancreatic and colon cancer cell lines at nanomolar concentrations. The San A derivatives are of particular interest because they do not share structural homology with other classes of marketed cancer therapeutics, they appear to inhibit an established target (Hsp90) at a novel site, and they are significantly more potent than the drugs currently available for the treatment of colon and pancreatic cancer. Known Hsp90 inhibitors interact with the N-terminal domain whereas our compounds are unique in that they target the C-terminal domain and block the binding of inositol hexakisphosphate kinase 2 (IP6K2). It is the overall goal of this project to develop a novel chemotherapeutic agent based on the San A scaffold. It is our hypothesis that analogs of San A with even greater potency and selectively can be synthesized by modifying key structural features identified in our preliminary studies. The specific aims are to: a) Conduct structure-activity studies of San A derivatives and select a lead candidate compound, b) Identify the key cellular targets and determine the mechanism by which San A analogs kill tumor cells, and c) Determine the efficacy and toxicity of a lead San A derivative in colon and pancreatic xenograft models.